Field of the Invention
The present invention relates to a semiconductor device comprising a plurality of semiconductor chips.
Description of the Related Art
Recently, an increase in leakage current caused by heat generated by a transistor, a signal delay in an interconnection, and the like are becoming problems and limiting further micropatterning of semiconductor exposure processes. As a technique of breaking the limit of micropatterning in a plane, a three-dimensional packaging technique by which semiconductor chips are stacked and interconnected by a through via (vertical interconnect access) extending through the semiconductor chips is attracting attention. Also, a 2.5-dimensional packaging technique by which a plurality of semiconductor chips are arranged parallel on a silicon interposer having undergone the through via technique and are interconnected by a through via is similarly attracting attention.
When a plurality of semiconductor chips are stacked by the three-dimensional packaging technique, these semiconductor chips are electrically connected by a through via extending through the semiconductor chips. That is, the semiconductor chips are connected to a shared bus by the through via, or adjacent semiconductor chips are interconnected by bus connection.
When transferring data to a specific semiconductor chip between the interconnected semiconductor chips, a mechanism for performing selective transfer is necessary. As a method of performing selective transfer, there is a method of giving unique chip identifiers to stacked semiconductor chips. When the chip identifiers of a transmission source and transmission destination are added to data to be transferred, each semiconductor chip can determine whether the data is addressed to it. If the data is addressed to the semiconductor chip, the semiconductor chip processes the data. If the data is not addressed to the semiconductor chip, the semiconductor chip does not process the data or transfers the data to a next semiconductor chip.
As a technique of allocating chip identifiers to semiconductor chips, a technique of storing the chip identifier in an internal memory of each semiconductor chip before the semiconductor chips are stacked is known. Although this technique can allocate a given chip identifier to each semiconductor chip, it becomes necessary to identify the individual semiconductor chips when stacking them, and this decreases the efficiency and increases the cost. That is, it is desirable to allocate chip identifiers to semiconductor chips after they are stacked.
A technique of allocating chip identifiers to semiconductor chips after they are stacked has been proposed. In this technique, a chip identifier of a semiconductor chip is input by using a dedicated line of the chip. A semiconductor chip to which a chip identifier is input increments or decrements the input value, and outputs the incremented or decremented value as a chip identifier of a next semiconductor chip to a dedicated line of the next semiconductor chip. This technique can allocate a unique chip identifier to each semiconductor chip when the power supply is turned on.
Also, there is another technique by which semiconductor chips spread an instruction for fetching a signal value used in normal data transfer as a chip identifier by delaying the instruction. At a timing at which the instruction becomes valid in each semiconductor chip, an arbitrary chip identifier is allocated to the semiconductor chip by controlling the signal value used in normal data transfer.
In the above-mentioned techniques, however, dedicated lines for allocating chip identifiers are necessary, and this increases the number of interconnections. Also, to allocate chip identifiers to semiconductor chips, it is necessary to grasp the delay amount of the instruction for retrieving a signal value as a chip identifier.